i ran the 555 on the street and personally i think they are close to the stockers. i dont like them at all. et is what i see ppl running at the track and most of them started with nittos and switched...

i had this same intake and just about 2 months ago got the rotofab its a much better intake but costs about 150 more. but as far as u cant feel the diff. i wouldnt worry tomuch about it. my butt dyno...

im pretty sure most gm deals will say that will void ur warranty aswell. but a tune is saver if ur ok with no warranty. but some dealers will still warranty stuff with a tune (some not all but some)....